Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
629 PM EST Wednesday Nov 25 2015
high pressure into Friday with warming trend. Cold front sags
southeast Friday night and Saturday...then waffles back and forth
before moving through Tuesday/Tuesday night. Colder middle week.
Near term /through Thursday/...
630 PM update...
No significant changes made to forecast tonight.
Previous discussion below...
No significant changes necessary to the near term period as things
look to be on track. High pressure...off to the east...with a warm
southeasterly flow across the area. Outside of periods of high
clouds...across the south this afternoon as a shortwave moves
through the area...and additional high clouds on Thursday out ahead of
approaching front...mostly sunny and dry conditions. Could be some
more extensive cloud cover Thursday across eastern slopes...as
low level moisture increases in the southeasterly flow...but no
precipitation is expected. Kept overnight temperatures towards the
cooler side of guidance...with above normal temperatures on
Thursday...particularly in favored downsloping regions.
Short term /Thursday night through Saturday/...
all models agree on continuing the slower trend on a cold front
approaching the area from the northwest...now not slated to cross the
middle Ohio Valley until Sat. The key to the forecast is how fast and
how far S a northern stream short wave trough progresses.
Slowed down the onset of the chance for precipitation Friday so that
much of the area enjoys another nice...mild day. The chance for
showers does not reach the middle Ohio Valley until late Friday...and
the central Appalachians until Sat morning. Rain showers are likely
throughout much of the area Sat...mainly through central portions of
the area...with the front dissecting the area from west-southwest to east-northeast by
late in the day.
With much of the precipitation along and behind the front...low
level ridging keeping Gulf and Atlantic inflow cut off for the most
part...and much of the upper level dynamics with the short wave trough
passing north of the area...the threat for heavy rainfall and
thunderstorms appears none.
Temperatures close to previous with bias corrected met / mav blended
in early on...then higher than previous for Sat given slower
progress of the baroclinic zone into the area...with GFS based MOS
guidance and NAM model data blended in.
Long term /Saturday night through Wednesday/...
the pattern for the Saturday night into next week is dominated by a
frontal boundary that waffles back and forth across our region.
Confidence in the timing and placement of this feature at any
particular time is low...so will keep some probability of precipitation through the
period...but not be overly specific. By Tuesday or Tuesday
night...models showing the front finally pushing through and
bringing colder air for middle week. Models vary considerably with the
timing of this front...so used a blend of continuity...the European model (ecmwf)
ensemble mean...and the naefs mean.
Aviation /23z Wednesday through Monday/...
VFR conditions during the period. Southeast winds...generally light
across The Lowlands...although occasional gusts across the higher
terrain in the upper teens to lower 20 knots range...including at
site kbkw through 04z. May have some stratus developing on eastern
slopes late tonight/early Thursday...but not expected to cause any
flight restrictions at kbkw at this time. Southeast flow will continue on
Thursday with 15 to 20 knots gusts at kbkw. Looking at mainly a broken
to overcast cirrus during the day.
Forecast confidence and alternate scenarios through 00z Friday...
Forecast confidence: high.
Alternate scenarios: none
Experimental table of flight category objectively shows consistency
of weather forecast office forecast to available model information:
h = high: taf consistent with all models or all but one model.
M = medium: taf has varying level of consistency with models.
L = low: taf inconsistent with all models or all but one model.
UTC 1hrly 22 23 00 01 02 03 04 05 06 07 08 09
EST 1hrly 17 18 19 20 21 22 23 00 01 02 03 04
crw consistency h h h h h h h h h h h h
heights consistency h h h h h h h h h h h h
bkw consistency h h h h h h h h h h h h
ekn consistency h h h h h h h h h h h h
pkb consistency h h h h h h h h h h h h
ckb consistency h h h h h h h h h h h h
After 00z Friday...
IFR possible in low clouds and rain Saturday night into